Time delay magnetic starter



Feb. 14, 195o T. w. FRECH 2,497,54

TIME DELAY MAGNETIC STARTER Filed June 27, 1947 Inverow Theodore W.Frech,

His 't'ormeg.

Patented Feb. 14,i 1950 TIME DELAY MAGNETIC STARTER Theodore W. Frech,Cleveland, Ohio, assignor to General Electric Company, a corporation ofNew York Application June 27, 1947, Serial No. 757,431

Claims. l My invention relates to electric discharge devices of the typeemploying ionizable mediums such as gases or vapors, and moreparticularly to starting and operating devices and circuits therefore.

Circuits now in Wide use with iluorescent lamps are provided with meansfor heating the lilamentary electrodes and for impressing a high voltagefor a short duration across the electrodes for starting an electricaldischarge therebetween.v

l starting occasioned by lingering preheating periods, and varying orerratic operating characteristics with age.

An object of my invention is to provide a new and improved circuit forstarting and operating electrical discharge devices employingiilamentary electrodes.

Another object of my invention is to provide a new and improved meansfor impressing starting voltages across lamentary electrodes of anelectric discharge device which after a predetermined inverval of timeafter the initiation of current iiow through the electrodes impressesstarting and operating voltages thereacross.

A further object of my invention is to provide a new and improvedstarting device for electric discharge devices which embodies arepetitive magnetic switch of the vibratory type accurately controlledby a thermal element.

In accordance with my invention I provide a new and improved startingdevice and system for iluorescent lamps wherein there is obtained anaccurately determined and uniform period of electrode preheating whichis reduced to a minimum or optimum value without sacrificing adequatepreheating of the electrodes, thereby substantially avoiding theundesirable long Waits in starting the lamps but without imposing severel operating conditions on the lamps.

` erence may be had to the following description taken in connectionwith the accompanying drawing and its scope will be pointed out in theappended claims. Fig. 1 is a diagrammatic view of an electric dischargedevice and a starting and v operating circuit therefore incorporating myinvention Fig. 2 illustrates schematically the time delay magneticstarter shown in the circuit of Fig.1. Fig. 3 illustrates a modificationof the starting and operating circuit shown in Fig. 1. Figs. 3 and 4illustrate a commercial embodiment of a starting device embodyingcertain aspects of my invention.

Referring to Fig. 1, I have there illustrated one embodiment of myinvention as applied to an electric discharge device I. The electricdischarge device I, such as a fluorescent lamp, therein illustratedcomprises an elongated tubular or cylindrical envelope 2 having sealedinto the ends thereof lamentary electrodes 3 and 4, each hereinillustrated as comprising a coil, preferably in the form of a coiledcoil of tungsten wire activated with oxides of alkaline earth metals,such as a mixture of barium and strontium oxides. The envelope 2contains an ionizable atmosphere such as a rare gas-like neon, argon ormixtures thereof at a pressure of a few milimeters and a small quantityof mercury which, during the operation of the lamps, has a low pressureof the order of 10 microns. The device I may be a low pressure positivecolumn lamp of the fluorescent type provided with a suitable phosphor orfluorescent coating. This iiuorescent coating upon excitation by theradiation produced by an electric discharge between the electrodes,transforms a shorter wave radiation due to the discharge into longerwave radiation such as radiation within the visible range. For ease ofstarting, a stripe of strip 5 of conductive material which, for example,may be a metallic paint or graphite mixed with potassium silicate, maybe applied to a surface of the envelope. The starting strip 5 may beconnected to one or both of the electrodes.

In accordance with my invention the device I is connected across asuitable power supply circuit 6, 6 which for example may be a 115 volt,60 cycle alternating current source, for supplying current to device Ithrough the usual ballast 1 which serves as a starting inductance. Amanual make and break control switch 8 may be used to connect device Ito the power supply. A starting and operating circuit 9, 9 comprising aparallel circuit, including two branches in series with a thermal switchIIJ and thermionic electrodes 3 and 4 of device I, may include a voltagesensitive means II and a repetitive magnetic switch I2 comprisingcontact means I3, an armature I4, and a pair of high and low impedancewinding means I5 and IB, respectively. The thermal switch I0 comprises abi-metal strip I1,

i contacts I8 and a heater element I9 and may be,

,for example, a thermal switch such as that dis- 3 closed and claimed inUnited States Patent No. 2,236,697, granted April 1, 1941, on anapplication of L. R. Peters and assigned to the assignee of thisapplication. The contact means I3 of the repetitive magnetic switch I2shunts the voltage sensitive means I I and the high impedance windingmeans I5, and the contacts I8 of the thermal switch IU shunt the lowimpedance lwinding means I6. Heater element I9 of the thermal switch I0is in series relationship to both the electrodes 3, 4 and the parallelbranches of the starting cir cuit 9, 9. example, may be a glow dischargedevice having a critical or minimum break-down voltage or it may be ahigh resistance means. Preferably, such a glow discharge device has acritical breakdown voltage greater than the operating voltage y.

' contains ythe Voltage sensitive-means II in series withl the high andlow impedance windings I5 and I6, respectively, ofthe repetitivemagnetic switch I2. The other parallel branch of circuit 9,. 9'containsthe contact means I3, anvarma-V ture I 4v ofthe repetitivemagnetic switch I2in series With the` contacts IS and the bi-metal stripI1 of. the thermal switch I 0.

When theentire installation is energized by closing switch 8, currentflows through the ballast 'I, thermionic electrode 4, voltage sensitivemeans II, high impedance winding means I 5, low impedance winding meansI6, heater-element I9, and iilamentaryelectrode 3. Thehigh impedancewinding means I5 and the low impedance.

winding meansl actuate" the armature I4 substantially'instantaneouslyso; that the normally open contact means I3 engage each other-and shortcircuit thevoltagesensitive means II and the 4high impedance'winding I5.Contact means.,

I3, however, remain closed by reason ofrthe magnetic attraction ofthelowimpedancewndingA I6 for armature I4. Preheating currentfthuscontinues .to 4now through the ballast 1, electrode 4, contactmeans I3,armatureA I4, low impedance windingv means I6, heater element I9,andelectrode 3 until the heater element I9 actuates the bi-metal stripIIwhich in turn closes the normally open contacts I8 of the thermalswitch I0 and shunts the preheating current around the low impedancewinding means I6. Upon deenergization oi the low impedance winding meansI6, armature I4 is releasedand the current flowing` through thelamentary electrodes 3 and 4,

andthe ballast or inductance 'I is rapidly re. duced. At thispoint thelamentaryvelectrodes 3 and. 4 are suiciently heated to support anelectrical discharge therebetween, and the induced voltagesupplied bythe inductance 'I initiates van arc discharge between the electrodes.When `the discharge has vtaken place, the Voltage between the electrodes3- and 4 drops to'an operating voltage, as for example 60yvolts. Thevoltage sensitive means so designed thatk itsoperating,"voltagefis..above. this v.value and tmb-al1 The voltagesensitive means II, forA 4 practical purposes the starting circuit isdisconnected from the discharge circuit. The thermal switch IB thereuponcools, its contacts I8 open, and the switch is ready for another cycleof starting operations.

If device I does not ignite at the rst opening of the contact means I3of the repetitive magnetic switch I2, current again ows throughelectrode 4, voltage sensitive means II, high impedance winding means I5, contacts I8, bimetal strip Il, heater element I9, and electrode 3.Contacts I8. at this point are still in engagement with each otherbecause the design of the thermal switch is such that momentaryinterruptions ofcurrent through its heater element will not open itscontacts. Upon the now of currentagain through the high impedancewinding means I5, armature I 4 is actuated substantially instantaneouslyso that the normally open contact means I3 again engage each other andshort circuit the Voltage sensitive'means II and the high impedancewinding I5. Contact means I3 however, do not remain closed upon thissecond starting operation because. the low impedance winding means I6normally used for retaining the contact means I3 in engagement with eachother is not energized, butzshort circuited by the thermal contacts I8.Thus, the electromagnet switch operates as a repetitive magnetic switch'until'the discharge device I ignites.

The ignition or starting devices and circuits may be adjusted to thedischarge device I in such a manner that if the device I is faulty ornon- `operative the repetitive magnetic switch I2 will ceaseto operateafter a predetermined number of starting attempts. This is commonlyknown as the "lock-out arrangements in the. prior art. Although `thelock-outy arrangement is not Yherein shownor described it may beappledto this circuit;

Fig. 2 incorporates the samercorresponding parts shown in Fig. 1, butvillustrates more in detail thecomponentparts thereof.' A condenser 20shunts the starting devices of the starting circuit 9, 9.

Fig. 3 illustrates a modification of the starting circuit shown in Fig.1 and incorporates the `same vdescribed corresponding 3 parts thereofexcept the vvoltage sensitivemeans I I .therein illustrated as ,a glowlamp is replaced by a high resistanceelement At I. If desired, insteadofusing a glow lamp ora separate resistance element, the

.` winding means I5 and I6v may bey designed to afford sucientresistance or impedance in themselves for connection in the circuit.l

Figs. 4 and'5 illustrate avcommercial embodiment of my inventionA Inaccordance with my-invention,y I provide a starting and operating deviceand Circuit which will after a predetermined interval of time after theinitiation of currentv flow through the electrodes impress anoperating-voltage -thereacross .Accordingly, I provide av repetitivemagnetic switch of the vibratory type accurately, controlled by athermal element.

Generallyspeaking vI provide a starting device whichv will igniteanelectric discharge device one second after the initiation ofl current owthroughtheelectrodes thereof. Asindicated in Figs. 4and 5, Ihavevtherein illustrated a commercial embodiment of myinvention/comprising aninsulatingdisc or member 22;, acore structure--S11Pp,o.1rted;. by: dist- 22` and.; comprising a; rainer verticalmagnetic members 23 and a horizontal magnetic member 21! bridgingvertical members 23 of the magnetic switch I2, a horizontal rotatablearmature I4 supported by a non-magnetic structure 25 mounted on verticalmembers 23 and supporting at one end thereof the movable portion ofcontact means I3, stationary contact means I3, and actuating windingmeans I5 and I6 wound about horizontal member 24. Contact means I3comprising the stationary contact and the movable contact are actuatedby armature I4 and are connected across winding means I5 and glow switchII. Glow discharge device II has a critical breakdown voltage and isdesigned to establish closure of contact means I3 during an accuratelydetermined interval of time. Contacts I8 of thermal switch I0 areconnected across actuating winding means I6 for controlling the timedelay between the time of energization of winding means I5 and I6 andthe time of initiation of vibratory operation of armature I4. Condenseris supported on member 22 and shunts the complete starting circuit 9, 9incorporating my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a starting device for electric discharge devices having at leastone lamentary electrode, the combination comprising a repetitivemagnetic switch comprising normally open contact means, an armature andactuating winding means, said contact means being connected across aportion of said actuating winding means, and a thermal switch comprisingnormally open contacts connected across a diierent part of saidactuating winding means and a heater element located to actuate saidcontacts to closed position when heated and connected in series withsaid part of said actuating winding means to establish closure of saidcontact means during an accurately determined interval of time.

2. In a starting device for an electric discharge device of the typeemploying a iilamentary electrode, the combination comprising arepetitive magnetic switch of the vibratory type having contact meansconnected in series relation with said electrode, actuating windingmeans and an armature for actuating said contact means, a voltagesensitive device connected in series relation with said actuatingwinding means and having a critical breakdown voltage greater than thenormal operating voltage of said discharge device, said contact meansbeing connected across a portion of said winding means and the saidvoltage sensitive device, and a thermal means comprising contactsconnected across a different part of said actuating winding means and aheater element connected in series relation with said part of saidactuating winding means for short-circuiting said part of said actuatingwinding means a predetermined interval of time after the initiation ofcurrent ilow through said electrode to cause said magnetic switch toopen, said voltage sensitive element eiecting subsequent energizationsof the first-mentioned portion of said actuating winding means to causerepetitive closures of said magnetic switch irrespective of thecondition of said thermal element when said discharge device fails toconduct initially.

3. In combination, an alternating current supply circuit, an electricdischarge device comprising at least one lamentary electrode andemploying an ionizable medium, an inductive ballast in series with saiddevice, and a starting device connected across said electric dischargedevice in series with said lamentary electrode and comprising arepetitive magnetic switch including normally open contact means, anarmature and actuating winding means, said contact means being connectedacross a portion of said winding means, and a thermal switch comprisingnormally open contacts across a different part of said actuating Windingmeans and a heater element in series with said part of said actuatingwinding means to open said contact means at the end of a predeterminedinterval of time and to produce a transient starting voltage by thechange of current through said ballast.

4. In a starting device for electric discharge devices having at leastone filamentary electrode, the combination comprising a repetitivemagnetic switch comprising normally opencontact means, an armature andactuating winding means, a glow discharge device in series with saidactuating winding means and having a critical breakdown voltage greaterthan the normal operating voltage of said discharge device, said contactmeans being connected across a part of said actuating winding means andsaid glow discharge device, and a thermal switch comprising normallyopen contacts connected across a different part of said actuatingwinding means and a heater element in series with said magnetic switchand said glow discharge device to establish closure of said contactmeans during an accurately determined interval of time.

5. In combination with a gaseous electric discharge device comprising atleast one lamentary electrode, a main discharge circuit connected tosaid electrodes, and means for preheating said electrodes comprising astarting circuit connected across said main discharge circuit throughsaid electrodes, means for interrupting said starting circuit andimposing a starting voltage across said discharge device comprising ahigh resistance means in said starting circuit, a high impedance Windingand a low impedance winding of a magnetic closing means in series withsaid high resistance means, and a low resistance means of a normallyopen thermal switch in series with said high resistance means and saidhigh and low impedance windings, contact means actuated by said high andlow impedance windings shunting said high resistance means and said highimpedance winding, and normally open thermal means shunting said lowimpedance means.

6. A vibratory magnetic switch comprising an insulating member, amagnetic core structure supported by said member, an armature, actuatingwinding means and normally open contact means actuated by said armature,said Contact means being connected across at least a part of saidwinding means, and a thermal switch including a heating elementconnected in series with said winding means and having normally opencontacts actuated to closed position by said heating element uponheating thereof and connected across a different part of said windingmeans for controlling the time delay between the instant of energizationof said winding means and the time of initiation of vibratory operationof said armature.

7. A vibratory magnetic switch comprising an insulating member, amagnetic core structure supported by said member, an armature, actuatingwinding means and normally open contact means actuated by said armatureand connected across a part of said winding means, and a'fthermalffswitoh .including normally :open v`c onta'cts yneticfcorestructure .supported by Vsaid .memloeigA 'an armature, actuating"Winding means andnormally open contact means vactuated by saidfarma'ture and connected vacross .atleast a part of :said rWindingmeans, a `glow discharge device connected in series with asaid'actuating winding meanszand'liaving afcritica'l breakdown voltage toestablish lclosure of saidA -eontact means `during `an accuratelydeter-minable Yinterval tof time, 'and a thermal switch. includingnormally 'open `contacts 'connected' across a different part `of saidwindingmeans for controlling the time delay :betweenthe instant ofenergization 'of y'said Winding vn'leans and the 'time 'of initiationo'f vbratory :operation of said armature.

S9. A starter comprising the combination of a rmagn'etic relay'including a vhigh Limpedance lactuating winding and alow impedance'holding winding, an Iarmature 'and fa pair of normally open Acontacts:actuated by 'said armature 'and conneo'ted'in multiple yWith Ithe 4high"impedance Winding and in series with the low impedance winding, 'andathermal switch including a heater element connected in series with therelay windings and having normally lopen contacts actuated by saidheater `element :and connected sinrmultiple. with :the .said low:impedance Winding;

'.11'0. .A starter comprising .the :combination .fof a voltage sensitivedevice, ia :magnetic relay 'clllding respectively high 'and Flowimpedance 'ac-f tuatin'g .andfholdingxwindings in series with 'saidvoltage sensitive device, 4'anda pair of normally l'open fconta'ots:actuated by rsaid armature 'and connected in multiple with both the.high im :pedance Winding :and the said voltage Vsensitime device, and athernralswitch including :a Cheater element .connected .in :series withthe 'relay Wi-nd,- ings and :the voltage :sensitive device `and Ahay-ingenormailly Vopen contactsfactua-ted 'by said heater Velement and'connectedin multiple Witl'i the Ysaid lewimpedance winding.

'THEODORE W.

YREFEREN CES CITED y T-he following references are 'of record in thelfile 'di this -patent:

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